How can I get this gui based board game to work?

The gui changes are only visible to the first person to join the game, and even then not all player slots change to the player's profile image. Here's the script:

function PlayerAdded (player)
    if game.Players.NumPlayers == 1 then
        script.Parent.Player1.Image = "http://www.roblox.com/Thumbs/Avatar.ashx?x=100&y=100&username=" ..player.Name
    end
    if game.Players.NumPlayers == 2 then
        script.Parent.Player2.Image = "http://www.roblox.com/Thumbs/Avatar.ashx?x=100&y=100&username=" ..player.Name
    end
    if game.Players.NumPlayers == 3 then
        script.Parent.Player3.Image = "http://www.roblox.com/Thumbs/Avatar.ashx?x=100&y=100&username=" ..player.Name
    end
    if game.Players.NumPlayers == 4 then
        script.Parent.Player4.Image = "http://www.roblox.com/Thumbs/Avatar.ashx?x=100&y=100&username=" ..player.Name
    end
    if game.Players.NumPlayers == 5 then
        script.Parent.Player5.Image = "http://www.roblox.com/Thumbs/Avatar.ashx?x=100&y=100&username=" ..player.Name
    end
    if game.Players.NumPlayers == 6 then
        script.Parent.Player6.Image = "http://www.roblox.com/Thumbs/Avatar.ashx?x=100&y=100&username=" ..player.Name
    end
end

game.Players.ChildAdded:connect(PlayerAdded)